Collecting Micro-Organisms From The Arctic Atmosphere

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3. a. 3

4"

THE SCIENTIFIC MONTHLY

JANUARY, 1935

COLLECTING MICRO-ORGANISMS FROM THE
ARCTIC ATMOSPHERE

... , By FRED C. MEIER

COOPERATIVE INVESTIGATIONS, BUREAU OF PLANT INDUSTRY AND
WEATHER BUREAU, U. S. DEPARTMENT OF AGRICULTURE

WITH FIELD NOTES AND MATERIAL

By CHARLES A. LINDBERGH

When the red-winged monoplane
piloted by Charles A. Lindbergh soared
away from Flushing Bay on July 9,
1933, bound for aerial exploration near
the Arctic Circle, there began an un-
usual botanical collecting trip. Mrs.
Lindbergh was prepared to fly the ship
during intervals when her husband
might be occupied with manipulation of
an instrument new to transatlantic air-
planes — so new, in fact, that it was com-
pleted just in time for the writer to
carry it by plane from Washington to
New York to be added to other scientific
equipment which had been assembled for
the expedition. With this new device,
which, being untried, was noncom-
mittally called the "sky hook," it was
planned to make collections of micro-
organisms from the atmosphere along
the course of flight. As an incidental
feature of their aerial voyage, the two
flyers were cooperating with the U. S.
Department of Agriculture in its studies
of the epidemiology of rusts and other
plant diseases. .It was also hoped that
identification of materials collected at
various altitudes between points on the
course might contribute to our knowl-
edge of the movement of air currents in
northern regions.

History of Air-Content Studies
While it is generally known that bac-
teria, spores of higher fungi and pollen
grains are present among dust particles
in the atmosphere near the earth's sur-
face, much detailed information of prac-
tical value remains to be revealed by
further research. The aerial movement
of pollen from certain flowering plants
concerns the physician who deals with
"hay fever" and related troubles. The
plant pathologist and the medico-
pathologist are interested in obtaining
facts concerning the part that air cur-
rents may play in disseminating repro-
ductive bodies of organisms that cause
specific diseases of plants and animals.
Definite information of this sort is ob-
viously an aid to a well-planned control
program. As early as 1921 airplanes
were used in making collections of rust
spores as an aid to planning the bar-
berry-eradication campaign for the con-
trol of stem rust of small grains. This
work, by E. C. Stakman, 1 A. W. Henry,
G. C. Curran, W. N. Christopher and
pilots of the Army Air Corps, in the
course of cooperative investigations of
the U. S. Department of Agriculture and

i Stakman et al., Jour. Agr. Research, 24,
1923.

MICRO-ORGANISMS FROM ARCTIC ATMOSPHERE 7

40 30 20 10 O

Courtesy of The National Geographic Societv
Fig. 2. Map showing routes flown and points between which collections were made.
Numbers indicate individual collections and refer to records some of which are given

in Figures 8 and 9.

his "Introduction to Cryptogamic Bot-
any":

Other spores are wafted about in the air,
where they may remain for a greater or less
period, till, obeying the natural laws of gravity,
they descend in some distant regions. The trade
winds, for instance, carry spores of Fungi mixed
with their dust, which must have travelled
thousands of miles before they are deposited.

Pasteur, 4 using an aspirator, con-
ducted measured quantities of air
through gun cotton, dissolved the cot-
ton and examined the sediment with the
microscope. By this means and his
classical experiments involving the in-
troduction of air from various sources
into flasks of sterilized nutrient solution,

3 Berkeley, ' ' Introduction to Cryptogamic
Botany," London, 1857, p. 258.

4 Pasteur, Compt. Send. Acad. Sci. (Paris),
50, pp. 303-307, 1860.

the University of Minnesota, stimulated
other such studies. Similar rust spore
collections were later obtained by plant
pathologists in Canada, Germany and
Russia.

Since the microscope first came into
use, studies of micro-organisms in the
atmosphere have been of absorbing in-
terest to botanists and medical men. It
was in 1830 that Ehrenberg 2 first pub-
lished on microscopic objects which he
found present in atmospheric dust.
Later lie reported finding infusoria in a
dust sample collected by Darwin when
on board the Beagle near Porto Praya.
Perhaps inspired by the studies of
Ehrenberg, Berkeley, 3 in 1857, writes in

2 Ehrenberg, Ann. Phys. u. Chem., Jahrgang
1830, Viertes Stuck, Vol. 17-18, pp. 477-514,
1829-30.

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THE SCIENTIFIC MONTHLY

Photograph by If. L. F. Foubert
FIG. 3. THE "SKY HOOK"
Built around a piece op aluminum tubing 1 inch in diameter and 42 inches in length.
When in use, the lower end of the tubing slips into a bracket provided tor the purpose

AT THE LEFT FRONT OF THE FORWARD COCKPIT. In THIS POSITION, THE TUBING PROJECTS VERTI-
CALLY TO A HEIGHT APPROXIMATELY 2 FEET ABOVE THE EDGE OF THE COCKPIT. THE UPPER END
OF THE TUBING CARRIES TWO GUIDES INTO WHICH INTERCHANGEABLE ALUMINUM CARTRIDGES (FlG.
4) CAN BE SLIPPED AND FIRMLY FASTENED IN POSITION. AFTER THE UNEXPOSED CARTRIDGE IS
ATTACHED TO THE HANDLE AND THIS IS CLAMPED INTO POSITION, THE ENTIRE OPERATION OF EXPOS-
ING THE SLIDE AND RETURNING IT TO THE CONTAINER CAN BE CARRIED OUT BY MEANS OF AN ALU-
MINUM PULL-PUSH ROD OPERATED FROM BELOW, THUS AVOIDING DANGER OF CONTAMINATION FROM
HANDS AND CLOTHING. ILLUSTRATION SHOWS : A, HANDLE READY TO RECEIVE CARTRIDGE ; B, CAR-
TRIDGE INSERTED AND READY TO BE PROJECTED INTO AIR STREAM; C, SLIDE PULLED INTO EXPOSURE
POSITION; D, SLIDE RETURNED TO CYLINDER AFTER WHICH CARTRIDGE IS REMOVED AND SEALED.

MICRO-ORGANISMS FROM ARCTIC ATMOSPHERE 9

l'hotoaraph by M. L. F. Foubert
FIG. 4. EACH SLIDE CONTAINER OE CARTRIDGE CONSISTS OF TWO

MAJOR PIECES

One of these is an outer shell made from a section of thin-walled aluminum tubing
4j" long and 11/16" inside diameter that is permanently sealed at one end and open at
the other. the second part is an aluminum rod that is cut away to form a flat sur-
face the length of the glass slide. the slide is firmly attached to this flat surface
by means of a screw device. this inner aluminum bar terminates in a cap piece pro-
vided with a seal made of a short section of gum-rubber tubing held in position
by machined points. when the slide is in the cylinder, the gum rubber provides a suf-
ficiently tight-fitting connection to prevent contamination from the outside. when
the bar and mounted slide have been withdrawn to the exposure position with the
petrolatum-coated surface facing the air stream, a check ring on the control rod stops
the withdrawal at a point that leaves the upper end of the slide bar supported against
the lower rim of the cylindrical container. the illustration shows a slide carrying
bar before being placed in the adjacent cylinder. beside these is a loaded, paper-
wrapped cylinder which was carried on the trip and returned unused. at the extreme
right is an exposed cartridge as returned to the laboratory. immediately after expo-
sure the cartridge was sealed with adhesive tape and the collection number was re-
CORDED. Tape was applied at the top to prevent a possible breaking away of the cap
piece. This, however, in no instance occurred.

lie proved that there are living hacteria
and mold spores in the air and that the
numbers vary considerably in different
locations.

The many studies of air content con-
ducted by nineteenth-century medical
men in their efforts to combat epidemics
of cholera and other diseases are re-
viewed by Cunningham 5 in a paper re-

5 Cunningham, "Microscopic Examinations
of Air," Calcutta, 1873.

porting his studies of air pollution,
written while he served with the British
Government as surgeon in India. Pub-
lication of this paper in 1873 stimulated
bacteriologists in their studies of organ-
isms present in the air around them.

Advances made in the development of
aircraft early in the twentieth century
made it possible to extend the scope of
such investigations. All the earlier work
was based on examination of air as

10

THE SCIENTIFIC MONTHLY

I

mm
ill

mm
:1

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MICRO-ORGANISMS FROM ARCTIC ATMOSPHERE

11

found near the surface of the earth.
Although Pasteur considered the possi-
bility of conducting experiments from a
hot-air balloon, he decided that the
method presented too many difficulties,
so carried his flasks up the Jura Moun-
tains and the Montan Verte, where ex-
posures were made at 850 and 2,000
meters above sea level. The previously
mentioned studies of rust-spore move-
ment by use of spore traps on airplanes
suggested new possibilities for study of
dissemination of organisms that cause
plant diseases.

For example, the writer 6 has obtained
pure cultures of numerous fungi from
spores which he collected during train-
ing flights of the naval airship Los
Angeles in January and April, 1932, and
from airplanes in the course of investi-
gations begun in 1931 by the XL'S. De-
partment of Agriculture with the co-
operation of the Navy, Army and Coast
Guard air-service units. The ease with
which vigorous cultures of fungi have
been grown from spores collected during
these airplane flights, which were made
at various altitudes over widely scattered
coastal, desert, mountain, forest and
agricultural areas of the United States,
emphasizes the probability of long-dis-
tance movement of viable spores of cer-
tain saprophytic and parasitic organ-
isms.

The day-by-day situation with regard
to presence of micro-organisms at differ-
ent levels in the atmosphere over a given
territory was discussed by Proctor 7 be-
fore the American Academy of Arts and
Sciences in April, 1934. In his summary
of studies of 201 separate collections
secured from 45 airplane flights made
over Boston by the Meteorology Divi-
sion of the Department of Aeronautical
Engineering, Massachusetts Institute of

6 Meier et al, Phytopathology, 23, 1933.

* Proetor, Proc. Amer. Acad. Arts and Sci.,
Vol. 69, No. 8, Aug., 1934 (Contrib. Dept. Biol,
and Public Health, Mass. Inst. Teehnol., No.
29.)

Technology, he states: "Bacteria and
molds were found above 19,600 feet,
yeasts and pollens were found above
16,000 feet."

Significance op Northern
Collections
Although, prior to the Lindbergh At-
lantic Survey Flight, several investi-
gators have used airplanes as an aid to
study of micro-organisms present in air
currents, such collections from the upper
air have always been made over or near
land in latitudes where numerous species
of fungi growing on abundant local
vegetation were constantly liberating
spores. The opportunities for obtaining
significant data on long-distance move-
ments of spores and pollen would seem
particularly good in the case of ex-
posures made over water and ice of
northern latitudes as compared with
similar studies over land in the temper-
ate zone, where the collector may be con-
fused by much material originating from
local sources (Fig. 1). The suitability
of the course covered by Tingmissartoq
in 1933 for studies of this kind is evi-
dent from the photographs and excellent
descriptions given in Mrs. Lindbergh's 8
story of the flight and from the route as
indicated on the map (Fig. 2).

The "Sky Hook"

The collecting device for this particu-
lar trip was designed by Colonel Lind-
bergh (Figs. 3 and 4) with several
requirements in mind. It should be
compact, light in weight and simple to
operate. The containers enclosing the
collecting medium must be constructed
to prevent contamination before or after
exposure. They must be sufficiently

s Lindbergh, Anne Morrow. Foreword by
Charles A. Lindbergh", Nat. Geog. Mag., 66, pp.
259-337, 1934. In this story, Mrs. Lindbergh
tells of the christening of the plane: " 'Ting-
missartoq! ' Eskimos shouted when the mono-
plane circled overhead. So Tingmissartoq it
became — 'The one who flies like a big bird.' "

12

THE SCIENTIFIC MONTHLY

MICRO-ORGANISMS FROM ARCTIC ATMOSPHERE 13

strong to stand possible rough handling
without breakage. It was, of course,
also important that the collecting me-
dium used be such that material would
remain in condition for examination
some weeks or months after the sample
was taken. Colonel Lindbergh's knowl-
edge of pure-culture technique made
him thoroughly aware of the necessity of
developing a trap that could be used
with minimum danger of error resulting
from contact with dust in the cockpit.
From discussion of these various re-
quirements a plan was evolved for a
modification of the oiled microscope slide
trap. Glass slides with oiled surfaces
have frequently been utilized in aero-

a culture room. After a mount carry-
ing the petrolatum-coated glass slide
had been inserted in each cylinder, with
the gum rubber washer serving as a seal,
a band of adhesive tape was applied.
This served to prevent accidental open-
ing. The surface of the entire cartridge
and seal was then cleaned by moistening
with alcohol, followed by thorough
rubbing with sterile gauze, after which
the cartridge was wrapped in clean
sterile paper for protection until used.

Contamination from the Airplane
Unlikely

The low-winged monoplane Tingmis-
sartoq is an exceedingly trim ship, as is

Photograph by Charles and Anne Lindbergh. Used by special
permission. Copyright, National Geographic Magazine

FIG. 7. BLACK MOUNTAINS PUSH JAGGED POINTS THROUGH THE SNOW

a tip of the wing shows in the picture as the plane skirts the ice cap southward from

Clavering Island to Angmagssalik.

scopes by investigators working on the
ground, from roofs of buildings or from
aircraft. After a design had been devel-
oped, the services of the American Instru-
ment Company, of Washington, D. C,
were enlisted. The personal interest
taken in the project by both officers and
employees of this company made possible
"overnight" construction of the "Sky
Hook" and fifty cartridges.

In preparation for these northern
flights, the cartridges or slide containers
(Fig. 4), after having been thoroughly
cleaned, were loaded in the still air of

evident to those who have viewed her
graceful lines as she hangs suspended, a
central figure of the Lindbergh collec-
tion in the American Museum of Nat-
ural History (Fig. 5). Immediately
forward and below the cockpit wind-
shield is nothing but the smooth skin of
the fuselage. The exhaust is carried
away from the motor through a short
stack below the fuselage. Directly
ahead of the spore trap when in ex-
posure position were the propeller tips
only. In view of the fact that the writer
frequently has found it possible to

14

THE SCIENTIFIC MONTHLY

&y~~*XLb »-u> iJm^Jx, i&yjn ^»w, ./£«-». /**~&\

&*~y. aMLA 40 as -$(2,000 jk- sroo) J»~Jj-/2. c &>> */*J
IJrAiJi.. SJLj'tfo *<*~«J tttJ-JZoooft-. ^JU^

N0.7 (ULzz.mz* fl<ks. ~kmz4, AirUj 270' aJ^T is/LJ». &~~y.

cJboCf I OOO $t.). CJLs, o~J

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att.30OO$; J^^tll'C 6L>, A^xJ I/O . A~ fiy. C!Uy o~J uJL —

Fig. 8. Photogkaph of original pencil notes sent in by Colonel Lindbergh with the
slide containers. similar free-hand maps were provided for each slide description.

MICRO-ORGANISMS FROM ARCTIC ATMOSPHERE

15

/L (/3) &y 4,1933 - 16,2.1 f/i,/. /0~~JI ?0° e^J-JT/U^A,.

*J2T~ soccfit, — JjLJ O *C, &^ ^J*Jf I/O **~JL,

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<&a a£>J I la /t^.

g*~4&£s, <*£^J-<zt<?ooc #f(<rJU* JSt^jL&u,. tLJL

Fig. 9. Photograph from original pencil notes sent in by Colonel Lindbergh with the
slide containers. numbers refer to exposures indicated on the map (flg. 2).

secure clean slides during exposures at This particular ship had no such sur-

high altitudes, made by projecting the faces ahead. Being a seaplane, refuel-

collecting device over the side of the rear ing was carried on under conditions

cockpit of a biplane with the many sur- relatively free from dust stirred up by

faces ahead to collect dust when the surface winds (Fig. 6). Moreover, the

plane is on the ground, it is evident that speed of flight and consequent effective-

the rush of air when in flight quickly ness of air washing were greater by 30

and thoroughly removes dust particles m.p.h. than those obtained in biplanes

from these surfaces. ordinarily used by the writer.

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THE SCIENTIFIC MONTHLY

Twenty-Six Slides Exposed
Twenty-six collections were made dur-
ing the period from July 11 to August
26 on nights between North Haven,
Maine, and Copenhagen, Denmark.
Many of these were obtained while flying
over vast expanses of water, ice and
bleak mountainous country (Pig. 7).
With the expectation that the atmos-
phere of the far north would be thinly
populated with organisms, if any at all
were present, long exposures, thirty
minutes to sixty minutes, were made.
In previous work in southern latitudes
exposures of three to ten minutes at air
speeds ranging from eighty to one hun-
dred eighty miles per hour have been
found by the writer to give good results.
The territory covered is indicated on the
map shown in Fig. 2. Field notes by
Colonel Lindbergh, similar to those
shown in Figs. 8, 9 and 10, give circum-
stances surrounding each collection,
making possible interpretation of re-
sults. It must be remembered, however,
that frequently several days intervened
between collections. During these pe-
riods the botanical relationships were,
of course, changing as the season ad-
vanced. Wind direction and velocities
varied at times when different collections
were made. Moreover, unknown air
movements and atmospheric changes
were taking place between collections.
These factors must all be considered in
attempts at correlating results.

In an account of the work sent from
Reykjavik Colonel Lindbergh wrote :

Before opening for exposure, all the cylinders
were left in the air stream from three to five
minutes. They were all closed while still in
position and were sealed with adhesive tape
without again being opened. It was not possi-
ble, however, to avoid sometimes touching the
knurled end, and the tape, of course, was ex-
posed to the turbulent air in the cockpit.

Hence, at his suggestion, before the
slides were removed for laboratory
examination, the exterior of the cylin-

ders, including the area covered by the
tape, was flamed to destroy any micro-
scopic objects which might have adhered.

Examination of Slides
Following their return to AVashing-
ton, the cartridges were left unopened
until each slide could be studied. In
preparation for examination, the cylin-
der was flamed, the slide was removed in
the still air of a culture chamber, and a
permanent mount was made. This was
done by adding a small quantity of
filtered lactophenol to the exposed sur-
face, covering the preparation with a
flamed clean strip of No. 1 cover glass,
and, finally, after the preparation had
been allowed to rest several days in^a
desiccator, sealing it with lanolin
cement. Counts were then made over a
five square centimeter area while
traversing the slide laterally with a
three millimeter dry objective and 15x
ocular, and photographs were taken of
distinctive spores or pollen grains with
this same lens combination. In some
instances the camera lucida was em-
ployed for the work of recording. The
position of different objects was re-
corded on the mechanical stage, and
descriptive notes, including ocular
micrometer measurements, were made of
distinctive types.

Check Slides

Six slide containers, returned unused
after having been carried throughout
the trip, were employed as checks.
Careful microscopic examination of the
slides within demonstrated these to be
free from spores and pollen grains.

Numerous examinations of petrolatum
from the lot used in preparing the slides
for the trip, likewise gave confidence in
results obtained.

Discussion of Results
In these collections are found spores
of fungi, pollen grains and fragments of

MICRO-ORGANISMS FROM ARCTIC ATMOSPHERE 17

\

Fig. 10. Route maps drawn in the field by Colonel Lindbergh served to mark points
between which collections were made.

fungous liyphae. In some instances the
asci of certain fungi, apparently carried
up just before discharge of spores, were
caught, the spores being spattered about
by the impact. In addition were found
unicellular algae, fragments of fila-
mentous algae and insect wings, diatoms,
objects tentatively identified as sponge
spicules, volcanic ash and glass, and
other microscopic debris of the air.

It is not the purpose of this paper to
give detailed descriptions of the fungous
spores caught. Instead, descriptions,
tentative identifications and correlation
of information obtained from different
slides are reserved for a later paper.
The two figures 11 and 12 will, how-
ever, serve to give an idea of the variety
of material collected over Davis Strait
and Northeastern Greenland.

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THE SCIENTIFIC MONTHLY

MICRO-ORGANISMS FROM ARCTIC ATMOSPHERE

From camera-htcida drawings by F. C. Meier
Fig. 12. Types of objects trapped above the Arctic Circle ox smde 15. X970. (See

Figs. 2 and 9.)

20

THE SCIENTIFIC MONTHLY

Fig. 12 is the result of a careful ex-
amination of five square centimeters
surface of slide 15. This slide was ex-
posed on August 6 for forty minutes at
an average altitude of 3,000 feet above
sea level over the coast of Greenland
between Scoresby Sound and Clavering
Island, north of 70 degrees latitude and
well above the Arctic Circle. Wind was
from the west, about 15 m.p.h. The
complete data for this exposure are
given in Figures 9 and 10. Fifty-three
different types of objects were found on
this slide, duplication of some bringing
the total number up to one hundred and
ninety-three. A similar area on slide 9,
exposed over Davis Strait sixteen days
earlier than slide 15, was found to con-
tain approximately 70 different objects
and a total of 238 (Fig. 11). This slide
was exposed for 1 hour on July 22 at an
average altitude of 3,000 feet as the
plane approached Godthaab, Greenland.
Wind was from the west about 15 m.p.h.
(Fig. 8) . Nearest land to windward was
Labrador.

Critical study of such slides must
obviously be limited to objects that have
sufficient size and character to make
possible their identification. Often in
the case of fungous spores, it is impos-
sible to establish identity. In other
instances, one can at least feel sure of
the genus. Often the presence of a bit
of mycelium or relationship of similar
spores on the slide gives a clue. Plant
pathologists, mycologists and other bota-
nists acquainted with pollens will recog-
nize certain familiar types among those
shown on Figures 11 and 12. Among
the spores on those two slides are forms
which have been tentatively assigned to
various genera, among them being
Macrosporium, Cladosporium, Lepto-
sphaeria, Mycosphaerella, Trichothe-
cium, Helicosporium, Uromyces, Cama-
rosporium and Venturia. It is hoped
that with the aid of specialists on dif-

ferent groups of fungi, lichens, mosses
and flowering plants the number of posi-
tive identifications may be increased.

Writing in Mycologia early in 1934,
Jakob E. Lange 9 says:

But stronger and more lasting than any
other impression is the evidence of the wonder-
ful cosmopolitanism of the Agarics. When you
have once found, in a Danish Sphagnum-bog,
a few specimens of the "new" species Stro-
phanti psatliyroides Lange, it gives you a
shock to meet with the very same plant in a
bog in Oregon, near the Pacific Coast — and
only an hour later to come upon Lepiota cygnea
Lange, of which the only known specimens were
hitherto those gathered in 1925, a few miles
from my Danish home!

Who can trace the aerial course of the spore?

This Lindbergh collection of micro-
organisms from the atmosphere is the
first of its kind to give concrete evidence
of the part played by air currents in
distribution of fungi between northern
lands. The slides show certain spore
types to be abundant over Maine and
Labrador and present in diminishing
numbers as collections progressed to lee-
ward over Davis Strait, the great ice cap
of Greenland and Denmark Strait.
Some of the spores of fungi caught at
different points show definite evidence
of having been alive when trapped, for
they started to send out germ tubes
in the unfavorable petrolatum medium.
While, as would be expected, the collec-
tions show this northern air to be more
thinly populated with micro-organisms
than that over the continents in more
temperate regions, it must be realized
that, when one viable spore is precipi-
tated to water or vegetation under sur-
roundings capable of sustaining growth,
reproduction may be very rapid. The
potentialities of world-wide distribution
of spores of fungi and other organisms
caught up and carried abroad by trans-
continental winds may be of tremendous
economic consequence.

s Lange, Mycologia, 226, pp. 1-12, 1934.